Health Policy$ense

The Effects of the ACA’s Under-26 Mandate: What Do We Know?

Since September 2010, the ACA has allowed young adults to remain dependents on their parents’ private health plans until age 26. We are just beginning to understand the full impact of the under-26 mandate on the health and health care of young adults. Three new studies fill in some of the gaps.

Here’s what we know thus far, from studies that make good use of slightly older populations as a control group and a difference-in-difference method to adjust for contemporaneous trends in the pre- and post-ACA periods:

  1. It accomplished its immediate goal of expanding coverage. The mandate led to a 3-7 percentage point gain in coverage rates for an age group with historically high levels of uninsurance. Two new studies confirm this finding, pointing toward the higher end of the estimate. In a study published today in JAMA, Chua and Sommers estimate a 7.2 percentage point gain in coverage using Medical Expenditure Panel Survey (MEPS) data. Last month in an NBER working paper, Barbaresco et al.found similar gains for this age group, using Behavioral Risk Factor Surveillance System (BRFSS) data. 
  2. It increased self-reported access to care.  Barbaresco’s study confirmed earlier estimates by Sommers et al. based on the National Health Interview Survey.  Barbaresco estimates that the mandate increased the likelihood of having a primary care doctor by 1.8-3.9 percentage points, and decreased the probability of having foregone care because of cost by 2.2-2.8 percentage points. This is consistent with Chua and Sommers’ estimates that the mandate reduced annual out-of-pocket expenditures by 18% (from an unadjusted mean of $546.11).
  3. It improved self-assessed health status, at least at the upper end of the scale.  Barbaresco’s study found that the mandate increased the probability of reporting excellent overall health by 2.1-2.4 percentage points. Chua and Sommers found an even greater effect, an increase of 6.2 percentage points in the probability of reporting excellent physical health, and an increase of 4.0 percentage points in the probability of reporting excellent mental health. However, Barbaresco et al. found no effects on outcomes reflecting more severe health problems, such as days with health-related functional limitations, or days not in good mental or physical health. The authors suggest that “most of the mandate’s effect on health occurs by transitioning young adults from very good to excellent health, which is perhaps not surprising given the high baseline health level of this age group.” Subanalyses showed that the positive health effects were concentrated in college graduates.


We know less about the impact of the effects of the under-26 mandate on health care use; two studies provide conflicting information.

In a new NBER working paper, Akosa Antwi et al. use the Nationwide Inpatient Sample to estimate changes in hospital use attributable to the mandate. In general, 19-25 year olds are a healthy bunch, and inpatient care is a rare but costly event for them. The authors calculate that just 5.4% of this age group had an inpatient visit in 2008, but these visits account for about 30% of the group’s total health care expenditures. The most frequent reason for hospitalization, aside from admissions related to childbirth, is mental health care.  

The authors estimate a 3.5% increase in the number of inpatient (non-birth) visits, driven mainly by admissions not through the ER. The number of mental health admissions increased by 9%, driven primarily by admissions through the ER. They found no differences in the intensity of treatments during hospitalization.

But the JAMA paper, using MEPS, finds no effect on health care use, including outpatient, inpatient, or emergency services, or use of prescription drugs. However, the study did not isolate non-childbirth related hospitalizations, nor ones specific to mental health. It was also not powered to detect small changes in utilization. In addition, Chua and Sommers used 26-34 year olds as a comparison group, while Akosa Antwi et al. used 27-29 year olds. The Barbaresco paper, using BRFSS data, found no effect on use of preventive care, such as well visits or pap smears, and a decreased probability of having a flu vaccination. That paper also used 27-29 year olds as a comparison group.

What should we make of these results? The preponderance of evidence thus far is that the mandate did not lead to large-scale changes in health care utilization, although it may have had a heterogeneous effect on certain health care services. Increases in hospital care would be in striking contrast to findings from Massachusetts, where coverage expansion did not increase inpatient admissions or mental health care by young adults. Akosa Antwi and colleagues explain:

We note that the health insurance expansion we study here is much smaller than other large-scale efforts such as the near-universal health insurance expansion in Massachusetts. In addition, we study the short-run effect of the ACA health insurance expansion on young adults, leaving for future work the examination of the long-run effects. The findings by Meara et al. (2014) of no change or decreases in the use of hospital-based mental health care by young adults after the Massachusetts health insurance reform could reflect the availability of outpatient mental health care providers in Massachusetts that might be absent in other states. This means that the interaction of demand and supply-side constraints could determine the long and short run impact of health insurance expansions.

It is clear that we have much, much more to learn about the effects of the under-26 mandate, including how it affects labor market decisions, different population groups, and longer-term patterns of coverage, use of health care, and health outcomes.